Water Country is a big summer water park on the edge of Portsmouth, built for slides, wave pools, lazy rivers, and a full day of family noise. It is not historic New England, but it fills a very real role on hot coastal trips with children.
Treat it as a weather-dependent outing rather than a cultural stop. The park is most useful for families staying around Portsmouth or the Seacoast who need a break from beaches, museums, and old houses.